Assessment of glycemic control after islet transplantation using the continuous glucose monitor in insulin-independent versus insulin-requiring type 1 diabetes subjects

Abstract

Background: The aim of this study was to assess and compare glycemic control using the continuous glucose monitor (CGMS, Medtronic Minimed, Northridge, CA) in type 1 diabetes mellitus (T1DM) subjects who are insulin-independent versus those who require insulin after islet transplantation alone (ITA).

Methods: Glycemic control was assessed using 72-h CGMS in eight T1DM subjects who were insulin-independent after ITA (ITA-II), eight T1DM subjects who were C-peptide-positive but insulin-requiring after ITA (ITA-IR), and eight non-transplanted (NT) T1DM subjects.

Results: Standard deviation of glucose values was not significantly different between ITA-II and ITA-IR subjects (ITA-II, 1.2 +/- 0.1 mM; ITA-IR, 2.0 +/- 0.3 mM; P = 0.072). Both ITA groups were more stable than NT subjects (NT, 3.3 +/- 0.3 mM; P = 0.001 vs. ITA). Mean high glucose values were significantly lower in ITA subjects compared with NT subjects (ITA-II, 10.5 +/- 0.6 mM; ITA-IR, 13.0 +/- 1.0 mM; NT, 16.1 +/- 1.1 mM; P = 0.002). Mean average glucose values were not significantly different among all groups (ITA-I, 6.7 +/- 0.2 mM; ITA-IR, 7.8 +/- 0.3 mM; NT, 7.7 +/- 0.6 mM; P = 0.198). Mean low glucose values were significantly higher in both ITA groups compared with NT subjects (ITA-II, 4.5 +/- 0.2 mM; ITA-IR, 4.3 +/- 0.3 mM; NT, 3.0 +/- 0.2 mM; P = 0.003). Duration of hypoglycemic excursions (<3.0 mM) was markedly reduced in both ITA groups (ITA-II, 0%; ITA-IR, 2.4 +/- 0.2%; NT, 11.8 +/- 4.2%). Glycated hemoglobin was not significantly different between ITA groups (ITA-II, 6.4 +/- 0.2%; ITA-IR, 6.5 +/- 0.3%) and was significantly higher in NT subjects (8.3 +/- 0.2%; P < 0.001 vs. ITA).

Conclusions: CGMS monitoring demonstrates that glycemic lability and hypoglycemia are significantly reduced in C-peptide-positive islet transplant recipients, whether or not supplementary, exogenous insulin is used, compared with non-transplanted T1DM subjects.